Messages in this thread | | | From | "Tian, Kevin" <> | Subject | RE: [PATCH v2 6/7] vfio/platform: Create persistent IRQ handlers | Date | Mon, 11 Mar 2024 01:55:48 +0000 |
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> From: Alex Williamson <alex.williamson@redhat.com> > Sent: Saturday, March 9, 2024 7:05 AM > > The vfio-platform SET_IRQS ioctl currently allows loopback triggering of > an interrupt before a signaling eventfd has been configured by the user, > which thereby allows a NULL pointer dereference. > > Rather than register the IRQ relative to a valid trigger, register all > IRQs in a disabled state in the device open path. This allows mask > operations on the IRQ to nest within the overall enable state governed > by a valid eventfd signal. This decouples @masked, protected by the > @locked spinlock from @trigger, protected via the @igate mutex. > > In doing so, it's guaranteed that changes to @trigger cannot race the > IRQ handlers because the IRQ handler is synchronously disabled before > modifying the trigger, and loopback triggering of the IRQ via ioctl is > safe due to serialization with trigger changes via igate. > > For compatibility, request_irq() failures are maintained to be local to > the SET_IRQS ioctl rather than a fatal error in the open device path. > This allows, for example, a userspace driver with polling mode support > to continue to work regardless of moving the request_irq() call site. > This necessarily blocks all SET_IRQS access to the failed index. > > Cc: Eric Auger <eric.auger@redhat.com> > Cc: stable@vger.kernel.org > Fixes: 57f972e2b341 ("vfio/platform: trigger an interrupt via eventfd") > Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
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